Thermoplastic printed film innersole for shoes

ABSTRACT

The present invention relates generally to a printed film innersole (PFI) and a process for making the same. The present invention provides to a PFI and a process for the construction of an innersole for post-insertion into a shoe that can have significant design details added to the bottom surfaces.

RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C. §119(e) from U.S. Ser. No. 60/562,893, filed on Apr. 16, 2004, the contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a printed film innersole (PFI) and a process for making the same. More specifically the present invention related to a PFI and a process for the construction of an innersole for post-insertion into a shoe that can have significant design details added to the bottom surfaces.

BACKGROUND OF THE INVENTION

The use of innersoles (a.k.a., insoles) for footwear, e.g., shoes, is well known in the art. Typically, innersoles are made of cast polyurethane both single density and with various cast elastomer drops, e.g., ethylene vinyl acetate (EVA) thermoformed insoles and other various thermoformable materials, i.e., thermoplastic materials. Other various cushioning materials are also utilized by die cutting sheet stock materials.

While conventional innersole devices may be suitable for the particular purpose to which they address, they are not as suitable for the construction of an innersole for post-insertion into a shoe that can have significant design details added to the bottom surfaces. A limitation of conventional innersoles are that they cannot be printed. Adding graphics to the innersole bottom offers unique design advantages. Another limitation of conventional innersoles are restriction in colors or other design features. This is both expensive and labor intensive.

There is a need in the art for devices suitable for construction of an innersole for post-insertion into a shoe that can have design details added to the bottom surfaces.

SUMMARY OF THE INVENTION

The present invention relates generally to a printed film innersole (PFI) and a process for making the same. The present invention provides a PFI and a process for the construction of an innersole for post-insertion into a shoe that can have significant design details added to the bottom surfaces. In one aspect, the invention provides an innersole comprising: a) a first layer made of a printed thermoformable film; and b) a second layer made of a one or more cast cushioning foam materials, wherein the second layer is positioned beneath and is distinct from the first layer and the first and second layers have planes being directly adjacent. In one embodiment of the innersole, the printed thermoformable film is a thermoplastic urethane film. In one embodiment of the innersole, the innersole further comprises a fabric layer contacted with the first layer made of the printed thermoformable film wherein the fabric layer is positioned on top of the printed thermoformable film. In one embodiment, the invention provides a shoe containing the innersole of the invention.

In another aspect, the invention provides a process of making an innersole comprising the steps of: (a) providing a thermoformable film; (b) printing at least one design element onto the thermoformable film to yield a printed thermoformable film; (c) forming the printed thermoformable film into a shell; and (d) casting a cast cushioning foam material directly into the shell. In one embodiment of the process, the thermoformable film is a thermoplastic urethane film.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figure depicts a preferred embodiment by way of example, not by way of limitation. The present invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawing. The invention is capable of other embodiments and of being practiced and carried out in various ways. Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIG. 1 illustrates one embodiment of the process of making a PFI device of the invention using thermoplastic urethane film (TPU). Panel A is a photograph of the clear TPU in roll form. Panel B is a photograph of TPU after printing. Panel C is a photograph of printed TPU after forming in a support tool. Panel D is a photograph of the bottom view of a PFI for a shoe.

DETAILED DESCRIPTION OF THE INVENTION

It is to be appreciated that certain aspects, modes, embodiments, variations and features of the invention are described below in various levels of detail in order to provide a substantial understanding of the present invention. The PFI for shoes according to the present invention substantially departs from the conventional concepts and designs of conventional innersole devices, by providing an apparatus primarily developed for the purpose of the construction of an innersole for post-insertion into a shoe that can have significant design details added to the bottom surfaces.

In one aspect, the present invention provides a PFI device for shoes that overcomes the shortcomings of the conventional innersole devices. In one embodiment, the PFI present invention comprises: a thermoformable film, a printed film, a formed shell and a cast cushioning foam materials. In one embodiment of the invention the thermoformable film is a thermoplastic film. In a preferred embodiment of the device, the thermoformable film is a TPU.

In one embodiment, the device of the invention is a PFI useful for post-insertion into a shoe that can have design details added to the surfaces of the device, e.g., bottom surfaces. The device of the invention offers significantly different design advantages over conventional devices. In one embodiment, at least one color design is added to the surface of the PFI device. In another embodiment, two or more colors appear in the design added to the surface of the PFI device.

In another aspect, the invention provides a process of printing designs in the flat and then thermoforming a shell into a device of the invention. That is, printing is performed in the flat utilizing at least one printing technique and then the printed thermoformable film is formed into the shell to yield the PFI device of the invention. In one embodiment of the process of the invention, a formed shell is created from the thermoformable film, e.g., TPU, into which soft cushioning foam can be cast.

Process of Making the PFI of the Invention

The invention provides a process for making a PFI device. The thermoformable films are first printed then formed into the shell configuration to provide a molded shape into which the castable foam is dispensed, formed and demolded. The process of making a PFI device of the invention comprises the steps of: (a) providing a thermoformable film; (b) printing at least one design element onto the thermoformable film to yield a printed thermoformable film; (c) forming the printed thermoformable film into a shell; and (d) casting a cast cushioning foam material directly into the shell.

Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the attached figure illustrates the process for making a PFI device of the invention. As noted above and shown on FIG. 1, in one embodiment, the PFI device of the invention comprises a TPU (panel A), a printed TPU (panel B), a formed shell (panel C) and a cast cushioning foam materials.

As shown in FIG. 1, panel A and panel B, the thermoformable film is printed in the flat sheet form prior to forming. Thermoformable films useful in the process of the invention are manufactured by means of extrusion or are blown films and are purchased in roll form or sheet form. Thermoformable films useful in the process of the invention are either TPU or other materials that offer the ability to thermoform and provide adhesion to the castable cushioning foam. TPU useful in the method of the present invention is commercially available (Deerfield Urethane, Bayer MaterialScience Company, Pittsburgh, Pa., USA).

Soft flexible thermoformable films are selected that have certain characteristics that can include, but are not limited to, e.g., a high coefficient of friction, good abrasion resistance, and are absent from any processing aids or slip aids. These thermoformable films have low coefficient of friction so as to reduce slipping or movement inside the shoe once inserted. TPU or other thermoformable films that provide both good adhesion of printing inks and cast cushioning material are useful in the process of making the PFI devices of the invention. For example, TPUs are useful in the PFI devices of the invention as they do not include slip agents that would impede the adhesion for both the printing inks and or the cast cushioning foam. Thermoformable films useful in the process of the invention are also generally soft and flexible to the hand and have the ability to be printed. The thermoformable film can be matte finish, gloss finish, or embossed. They can be printed to significantly cover the entire bottom of the formed innersole or be printed selectively to provide detail or graphics to the innersole design. Printing may completely cover the bottom so as to provide an opaque shell or can be light enough to allow a translucent look to view the cast cushioning foam component through the film. Printing can be both single color or multi-color.

In one embodiment of the process, the thermoformable film is printed by at least one screen printing technique. Other printing techniques useful for printing the thermoformable film in the process of the invention includes, but is not limited to, e.g., ink jet, flexography, and hot stamp printing technique. Screen printing, ink jet, flexography and hot stamp printing are know in the art. Printing can also be performed in rolls on high speed printing equipment. Specially formulated print inks compatible with the film materials are employed. Materials useful for screen printing are commercially available, e.g., U.S. Screen Printing Institute (Tempe, Ariz., USA). The inks must provide excellent adhesion to the film and be flexible enough to withstand the manufacturing process.

Once the inks are dry, substantially rectangular sheets are cut and the printed film is placed into a support frame that supports the entire perimeter of the cut sheet. The formed shell can be thermoformed or vacuum-formed to create a molded shell into which the castable cushioning foam is dispensed. As shown in FIG. 1, panel B and panel C, the printed thermoformable film, e.g., TPU, is formed to create a shell. Techniques useful to mold thermoformable film to create shell include, but are not limited to, thermoforming processes such as vacuum forming, match mold forming, pressure forming, and foam-in-place forming. In a preferred embodiment of the process, the printed film is formed by means of a thermoforming. In another preferred embodiment of the process, the printed film is formed by means of vacuum-forming operation. The printed film is heated substantially near its melt temperature. The frame with the printed film is then heated to a point that the material starts to deform. Typically, this is slightly below the actual melt temperature of the thermoformable film. Specifically, the support frame and softened printed film are introduced to the vacuum-forming tool. In one embodiment of the process, the frame is lowered down around the vacuum-forming tool until the film comes in contact with the vacuum-forming tool. Once the film contacts the tool surface a box closes around the perimeter of the vacuum-forming tool so as to provide a complete seal for the film. A vacuum is then pulled through and around the perimeter of the vacuum-forming tool. This draws the heated, printed film in close contact to the vacuum-forming tool. The film is then allowed to cool on the unheated mold surface wherein it returns to its original solid state. The vacuum is then released and the molded printed shell is carefully removed from the mold surface. The molded shell is trimmed of excess film materials. This molded shell can then be placed directly into a support tool that substantially supports the molded shell (FIG. 1, panel C).

In one embodiment of the process, a cast cushioning foam material is cast directly into the molded shell. During this process it is useful to support the molded shell with a support tool (see FIG. 1, panel C). A castable cushioning material is the dispensed directly into this shell by a mixing metering unit. This unit casts a predetermined amount of material directly into the open shell. Since the castable cushion material is a blown or expanded material, the mold shell is filled approximately 40% full. The cast foam material useful in the process of the invention is any castable foam material that will provide both cushioning properties as well as excellent adhesion to the formed shell. In a preferred embodiment of the process, the castable foam material is a water blown, polyether polyurethane foam. Such water blown foam is a flexible polyurethane foam in which the gas for expansion is carbon dioxide generated by the reaction between water and an isocyanate material. All flexible polyurethane foam is water blown, although auxiliary blowing agents are often used to obtain special physical properties. Water blown, polyurethane foam is commercially available from The Dow Chemical Company (USA). This material is dispensed directly into the molded shell that is supported by a support tool.

Once filled, the top mold is then closed to contain the foaming process. Once the mold is closed and clamped in place, the reaction of the castable material then causes the foaming to initiate. This foaming fills the mold and forms the final part shape. Fabrics may also be introduced and molded in place by means of temporarily pinning these to the support tool lid or top cover. These fabrics are then cast onto the top surface of the finished part. Once cured, (approximately 5 minutes) the molded assembly is removed form the support tool. To complete the process, this part is either die cut or trimmed to remove excess film, fabric and or the cushioning foam material to yield the PFI of the invention (FIG. 1, panel D).

Equivalents

From the foregoing detailed description of the invention, it should be apparent that the present invention provides a unique PFI for shoe innersole construction wherein the same can be utilized for the construction of an innersole for post-insertion into a shoe that can have design details added to the bottom surfaces, as well as method of making the same. Although particular embodiments have been disclosed herein in detail, this has been done by way of example for purposes of illustration only, and is not intended to be limiting with respect to the scope of the appended claims, which follow. In particular, it is contemplated by the inventor that substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims. With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. 

1. An innersole comprising: a) a first layer made of a printed thermoformable film; and b) a second layer made of a one or more cast cushioning foam materials wherein the second layer is positioned beneath and is distinct from the first layer and the first and second layers have planes being directly adjacent.
 2. The innersole of claim 1, wherein the printed thermoformable film is a thermoplastic urethane film.
 3. The innersole according to claim 1, further comprising a fabric layer contacted with the first layer made of the printed thermoformable film wherein the fabric layer is positioned on top of the printed thermoformable film.
 4. A shoe containing the innersole of claim
 1. 5. A process of making an innersole comprising the steps of: (a) providing a thermoformable film; (b) printing at least one design element onto the thermoformable film to yield a printed thermoformable film; (c) forming the printed thermoformable film into a shell; and (d) casting a cast cushioning foam material directly into the shell.
 6. The process according to claim 5, wherein the thermoformable film is a thermoplastic urethane film. 